Thermally-controlled circuit interrupter



April 1 1924.

T INTERRUPTER THERMAL Filed May 9, 1921 INVENTOR.

ATTORNEY Patented Apr. 1, 1924.

' UNITED STATES 'PATENTI- OF F I CE. c.

FREDERICK L. QUA, OF WISCONSIN, ASSIGNOR TO THE CUTLER; HAMMER EEG. 00., OF MILWAUKEE, WISCONSIN, A. CORPORATION OF WISCONSIN.

TBEBMALLY-CONTEOLLED CIRCUIT INTEBRUPTEB, 7

Application filed Kay 9,

2 '0 all whom it may concern:

Be it known that I, Funnnnrcx L. Rn Qua,

a citizen of the United States, residing at Milwaukee,in the county of Milwaukee and I State of- Wisconsin, have invented new and useful Improvements in Thermally-Com trolled Circuit Interrupters, of which the following is a full, clear, concise, and exact description, reference being had to the ac- 10 companying drawing, form ng a part of this specification.

This invention relates to thermally controlled circuit interrupters and more particularly to those of the fluid contact tyqg.

In a copending application of Erwin Stoekle, fi ed February 14, 1920, Serial No. 358,60l,is disclosed and claimed such a circuit interrupter adapted to' be sub'ected to electro-thermic influence of a sing e circuit for response of the interrupter and also adaptedto reset automatically, and the present invention has among its objects that of providing such a circuit interrupter adapted to effect response thereof under electro-ther-- mic'influence of anyoneof a plurality of circuits-such, for example, as theindividual phase lines of a polyphase circuit.

Other objects and advantages will hereinafter appear. so In the accompanying drawing wherein are illustratedcertain' of the forms which the invention maywassume in practice,

Figf lis a longitudinal sectional view thereof, certain typical circuit connections therefor being illustrated diagranmiatical- 1y; while,

Fi s.' 2 and 3 are similar views illustrat- 1 ing s ightly modified forms of circuit interru ter.

n the construction illustrated in Fi 1, as in said copending application, a tn 5 of'glass or other insulating material is provided terminally .with solid electrodes 6 and 7 normally electrically connected by a quantity 8 of liquid conductive medium hereinafter designated-as mercury, although ohviously other substances may be employed, .electro-thermic means being provided and ada ted uponincrease, above a given value, of the current traversing the same to effect vaporization of an intermediate portion of the column of-niercury for sudden expulsion of a portion-of the liquid mercury from the regionbetween said electrodes to thereby interrupt circuit therebetween, the mercury 1821. Serial No. 468,127.

so expelled bein received within a suitable reservoirlecate above the tube and in communication therewith as illustrated.

The tube 5 is preferably arranged in a vertical position as illustrated whereby following escape or condensation of the vaporization mercury, the displaced body of liquid mercury is adaptedtg flow back within the tube thereby re-esta ishingthe interru ted circuit.

aid tube, throughout the major ortion of its length of such diameter t at the column of mercury contained therein is too large to be intersected or electrically interrupted by any. airor gas bubble which is likely to become entrapped during'suchre- .fiux of mercury within said tube thus tending to effect positivenemlof the resetting action. Moreover? the mercury column is constricted asillustrated at 9 to revent forcing of bubbles of any apprecia le size past such constriction, whereas the electrode 6 is of a-length-sufiicient to project inwardly beyond such constriction of the mercury column, thus insuring against defeat of the resettingzaction by possible entrapment of a larger bubble .above such constriction. Said constriction also serves to promote positivenessand suddenness of the response of the circuit interrupter in a manner more fully disclosed" insaid copending ap lication but not im ortant herein.

n addition to the: oregoing features the instant device coinprises the additional elements to be now described, rendering the same responsive to electro-thermic conditions of any of a plurality of circuits.

To such end the column of mercury within the tube 5 is provided with one or more additional constricted portions such as that indicated at 10, the total number of constricted portions referably corresponding to the number of individual circuits to the electrical condition of which the device is designed to be responsive. .Further those portions of the mercury column located im mediately'below each of the constricted portions of such column are provided with individual heatingimeaus such as the coils 11 and 12 illustrated,said coilsbeing connected in the individual circuits adapted to in'- fliicnce response of the device.

Thus, upoxr'predetermined rise in current traversin any of said coils, vaporization of the ad acent portion of the mercury column occurs for suddenly expelling from the tube the liquid mercury located thereabove,

thereby interrupting circuit through the device, and upon escape from the tube or upon condensation of such vaporized mercury, the-"liquid mercury so expelled is to support the tube, similarly minimizes" transfer of hea from either coil to the other by radiation.

It thus results that each coil is adapted to exert its own peculiar influence upon the mercury column without material influence by the act-ion of the other coil, that is to say,

the temperature at which response of the device occurs due to energization of one 0011 is not ilfluenced to any material extent by any degree of heatin due to action of the' other coil less than the degree required to effect actual response.

If desired, the constricted portions of the mercury column other than the uppermost of such constrictions may be provided with solid conductive means such as the elements 14 and 15 of Figs. 2 and 3 respectively, thus insuring maintenance of electricalcontinuity through such constriction in the event of trapping of a large bubble of gas above such lower constriction.

The circuit connections illustrated in Fig. 1 are typical of those which may be employed for adapting the aforedescribed interrupter to the control of a three phase motor 16 or the like. Obviously said connections are such that upon a given degree vof overload in any phase of the motor circuit the interrupter is adapted to respond, de-energizin'g the closing winding of main switch 17 for interrupting the motor circuit, whereupon following the aforedescribed automatic resetting of the interrupter the motor may be restarted by means of push button 18.

Obviously if desired the form of the device may be modified in various ways; thus the tube 5 might be constructed U-shaped, the upper portions thereof being provided with individual mercuryreservoirs, both electrodes being similar to the electrodes 6 and the heatin coils being similarly arranged with re erence thereto.

lVhat I claim as new and desire to secure by Letters Patent is.

1. In a circuit interrupter, the combination with a column of conductive li uid and electrodes to be connected thereby, o electr0- thermic means subjecting said column-t0 influence of a plurality. of'circuits for eflectm interruption of electrical continuity ofsai column upon attainment of certain electrical conditions of any of said circuits, said column having means rendering the response,

thereof to influence of the electricalcondition of one of said circuits substantially independent of influence of the condition of other of said circuits.

2. In a circuit interrupter the combination with a column of conductive liquid, of electro-thernnc means for sub ecting said liquid to fluid pressureof-its own vapor for interruption of electricfabcontinuit thereof, said means includin i elements-su jected to in' fluence selective y by'idifierent circuits.

3. In a circuit interrupter the combination with a column of conductive liquid, of electro-thermic means for subjecting said liquid to fluid pressure of its own vapor for interruption of electrical continuit thereof, said means includin elementssu jected to influence selective y b different circuits, and means to minimize t e influenceiof each circuit'upon the response due to influence of other of said circuits.

4. A thermally controlled circuit interrupter comprislng a substantially vertical tube to contain a column of mercury, electrodes to be electrically connected by said mercury, means constricting the icross sectional area of said column at a plurality of points, a plurality of'electro-therin'ic devices, having independent circuit connections, associated with said column at regions ad acent the respective constrictions thereof or interrupting electrical continuity of said column, certain of said constrictions serving substantially to limit the influence of in- (lividual electro-thermic devices to the portions of the column respectively associated therewith. t

5. A thermally controlltegcircuit interrupter comprising 9. subs ntially vertical tube to contain a colum of mercuryymeans associated with said t to provide a reservoir thereabove and in communication therewith, electrodes to "be electrically connected by said mercury, means constricting the cross sectional area of said column at a plurality 0 "points, a. plurality of electrothermic d vices, having independent circuit connections, associated with jsaid'column at regions adjacent the respective*constrictions thereof for subjecting an intermediate ortion of said column to fluid pressure 0 its own vapor to force liquid mercury from said tube into said reservoir to thereby efi'ect sudden interrupting of circuit between said electrodes, certain of said constrictions serving to limit the influence of individual electrothermic devices to the portions of the column mes-nee respectively associated therewith, said tube being of such internal diameter as to permit reflux of the expelled mercury for automatic resetting following escape from the tube or condensation of the vaporized mercury.

6. In a circuit interrupter, the comhine tion with a column of conductive liquid heving a constricted portion and electrodes to be connected by said column of liquid in a relation to shunt said restricted POI'tiOiiOf the column of liquid, of electro-thermie means to subject said column to fluid pres sure of its own vapor for interruptin electrical continuity thereof between said clectrodes, said means including elements enhjected to influence of electrical conditions of different circuits respectively.

7.111s circuit interrupter, the combinetion with a column of conductive liquid havtrodes, said means including elements sub-' jected to influence of electrical conditions of di'li'erent circuits respectively, said column having :1 further constricted portion located within the region between said electrodes and serving to minimize the influence of tech of said elements upon the response due to other of said elements.

In witness whereof, I have hereunto suh scribed my name.

FREDERICK L. ETA. 

